The present invention relates to the field of apparatus for automatically turning a radio or television receiver off.
Timers are known for turning electronic equipment on and off at predetermined times. In radio and television receivers, such arrangements are utilized to turn the receivers on at predetermined times when a user wishes to be awakened and to turn the receiver off at predetermined times when stations go "off-the-air". The latter feature is useful as an energy conservation and safety measure should a user fall asleep.
Apparatus are also known for turning off receivers in the absence of any RF carriers with acceptable reception characteristics. Such apparatus employ signal detectors for evaluating properties of certain signals derived from received RF carriers.
Automatic turn-off apparatus of the timer and signal evaluation types require the addition of a considerable amount of special circuitry to receivers. Thus, there is a need for automatic turn-off apparatus which may be incorporated in receivers with only a small amount of additional circuitry.